By means of hybrid circuits having transformers, the two-wire path, for example a subscriber's line, can be d.c. isolated from the four-wire switching network of a telephone exchange.
Conventional transformers for signal transmission having a low attenuation and a low distortion at low frequencies, are very bulky.
It is an object of the invention to provide a hybrid circuit having a small-size transformer whose performance with respect to the signal transmission is at least comparable with that of the conventional transformers.